The field of the invention pertains to archery bows. The invention relates more particularly to a mounting system for adjustably mounting a bow limb to a bow riser of an archery bow, wherein the bow limb may be adjustably pivoted and laterally restrained relative to the bow riser.
Archery involves a high degree of shooting precision and accuracy which is possible in part due to advanced bow configurations and designs. In particular, many modern bows utilize flexible bow limbs which are attached to opposite ends of a rigid bow handle, i.e. bow riser. This arrangement, together with the use of wheels or cams in a compound bow, provides an increase in the mechanical advantage of shooting an arrow. Moreover, adjustment of the attachment or pivot angle between the limbs and the bow riser has the additional benefit of varying the amount of force imparted to the arrow for a given pull distance on the bow string. Consequently, the relative bowstring tension and draw force required to pull the bowstring can be suitably adjusted to a preferential setting.
Perhaps the greatest problem with adjusting the attachment angle, however, is the tendency of the bow limb to twist sideways or misalign relative to the bow riser when the bowstring is pulled and/or released. This tendency can profoundly disrupt a shooters aim and accuracy. To address this problem, various devices and methods have been developed which enable adjustment of the attachment angles between the two bow limbs and the bow riser while restraining the bow limbs from experiencing lateral motion relative to the riser.
For example, in U.S. Pat. No. 5,231,970, a bow limb construction is shown using a single bolt to adjustably attach to a bow riser, and having a bushing with an elliptical bore to seat the bolt on the bow limb. However, in this arrangement the single bolt fastener operates alone to laterally restrain the limb relative to the riser. This configuration may be insufficient to provide the support required against lateral movement, especially when the bolt is sufficiently removed from the riser to produce a large attachment angle between the limb and the riser. Furthermore, because the bolt has a natural tendency under high axial pressures to orthogonally align itself with a longitudinal axis of the bow limb and thereby pivot relative to the riser, its rigidly fastened attachment to the riser may produce undesirable transverse stresses in the bolt.
Additionally, in U.S. Pat. No. 5,433,792, a compound archery bow is shown having a bow limb pivotally secured to a bow riser by means of a bolt fastener. A laterally opening pocket is provided on the riser to receive a nut which receives and secures the bolt fastener. Unlike the '970 patent, however, the '792 patent provides a projection 64 on the riser which engages a notch 62 on the limb to restrain lateral movement. However, the relatively thin and narrow projection may not be sufficient in providing the necessary restraint to prevent lateral movement. Moreover, and similar to the '970 patent, the bolt is again prevented from pivoting relative to the riser, which can be mechanically inefficient when adjusting the attachment angle between the bow limb and riser.
In U.S. Pat. No. 5,280,779, an archery bow is shown provided with pivoting pocket members for attaching each limb to the bow handle. Each pocket has an upper recess for receiving and laterally supporting a limb, and pocket walls which extend away from the recess to straddle the sides of the handle. And in U.S. Pat. No. 4,261,320, a compound bow is shown having its bow limbs seated in a pocket formed in the riser itself in FIG. 23. In either case, the bow limb itself is seated in a pocketed area which supports the bow limb along its side edges. However, the wall structures providing the side restraining support in the '320 and '779 patents may not provide sufficient reinforcement to withstand large lateral loads. This can be seen in FIG. 23 of the '320 patent, where the bow limb is bordered by narrow sidewalls of the pocket portion of the riser, as well as in the '779 patent disclosing relatively thin shoulders 42, 44 of the recess. While suitably wide pocket sidewalls may provide greater lateral restraint, they may be unduly bulky and interfere with the overall slim design of typical archery bows.
In summary, therefore, it would be advantageous to provide a mounting system for adjustably mounting a bow limb to a bow riser, wherein the bow limb is laterally restrained relative to the bow riser in an efficient yet solid manner. Furthermore, an adjustable bow mounting system which pivotally compensates the strut assembly at various attachment angles would provide greater structural stability under the typically high bowstring tensions. It is also notable that due to the variations in bowstring tension which result from adjustment of the attachment angle, it would be further advantageous to provide a mounting system which measures and indicates relative bowstring tension at the various attachment angles.